| Photons with strong mutual attraction in a quantum nonlinear medium. Credit: Nature. Harvard and MIT scientists are challenging the conventional wisdom about light, and they didn't need to go to a galaxy far, far away to do it.

Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules – a state of matter that, until recently, had been purely theoretical. The work is described in a September 25 paper in Nature.

The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don't interact with each other – shine two laser beams at each other, he said, and they simply pass through one another."Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.

"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other," Lukin said. "What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn't been observed.

"It's not an in-apt analogy to compare this to light sabers," Lukin added. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."

To get the normally-massless photons to bind to each other, Lukin and colleagues, including Harvard post-doctoral fellow Ofer Fisterberg, former Harvard doctoral student Alexey Gorshkov and MIT graduate students Thibault Peyronel and Qiu Liang couldn't rely on something like the Force – they instead turned to a set of more extreme conditions.

Researchers began by pumped rubidium atoms into a vacuum chamber, then used lasers to cool the cloud of atoms to just a few degrees above absolute zero. Using extremely weak laser pulses, they then fired single photons into the cloud of atoms.

As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.

"When the photon exits the medium, its identity is preserved," Lukin said. "It's the same effect we see with refraction of light in a water glass. The light enters the water, it hands off part of its energy to the medium, and inside it exists as light and matter coupled together, but when it exits, it's still light. The process that takes place is the same it's just a bit more extreme – the light is slowed considerably, and a lot more energy is given away than during refraction."When Lukin and colleagues fired two photons into the cloud, they were surprised to see them exit together, as a single molecule.

The reason they form the never-before-seen molecules?An effect called a Rydberg blockade, Lukin said, which states that when an atom is excited, nearby atoms cannot be excited to the same degree. In practice, the effect means that as two photons enter the atomic cloud, the first excites an atom, but must move forward before the second photon can excite nearby atoms.The result, he said, is that the two photons push and pull each other through the cloud as their energy is handed off from one atom to the next.

"It's a photonic interaction that's mediated by the atomic interaction," Lukin said. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."

While the effect is unusual, it does have some practical applications as well."We do this for fun, and because we're pushing the frontiers of science," Lukin said. "But it feeds into the bigger picture of what we're doing because photons remain the best possible means to carry quantum information. The handicap, though, has been that photons don't interact with each other."

To build a quantum computer, he explained, researchers need to build a system that can preserve quantum information, and process it using quantum logic operations. The challenge, however, is that quantum logic requires interactions between individual quanta so that quantum systems can be switched to perform information processing."What we demonstrate with this process allows us to do that," Lukin said. "Before we make a useful, practical quantum switch or photonic logic gate we have to improve the performance, so it's still at the proof-of-concept level, but this is an important step. The physical principles we've established here are important."

The system could even be useful in classical computing, Lukin said, considering the power-dissipation challenges chip-makers now face. A number of companies – including IBM – have worked to develop systems that rely on optical routers that convert light signals into electrical signals, but those systems face their own hurdles.Lukin also suggested that the system might one day even be used to create complex three-dimensional structures – such as crystals – wholly out of light.

"What it will be useful for we don't know yet, but it's a new state of matter, so we are hopeful that new applications may emerge as we continue to investigate these photonic molecules' properties," he said.

Cr6, I greatly appreciate your topics for review and consideration, though I haven't been able to reply to them all.

This article is very similar to another article Miles cited in his recent paper, “Photons slowed below c? Not Really”, http://milesmathis.com/belowc.pdf, titled “Scientists slow the speed of light”, http://www.bbc.com/news/uk-scotland-glasgow-west-30944584

Miles wrote:I have no trouble believing they put photons through a mask, and that the photons were changed so that they no longer kept up with other photons. That is, I believe the particles coming out the other side were slowed below c. However, they were no longer photons, so photons were not being slowed below c. See the difference?

What was happening is that the photons were being spun up by the mask. If they were spun up enough, they became a species of electron. That's right. In my theory, an electron is just a spun-up photon. You can see the quantum spin equation that shows the particle hierarchy here. In the same way, a proton is a spun-up electron. So the particles coming out the far end of Dr. Padgett's mask are not strictly photons. They are level-1 spin electrons.

Miles seems unequivocal; photons cannot travel slower than c. Of course, I’ve had plenty of doubts. Does that mean that c is always 186,000 miles/sec? I always thought denser media reduced the speed of c. What is refraction? On the other hand, any media created by atomic matter is mostly transparent to photons, and so, how can that media possibly slow all photons passing through it?

Quoting your article above

Researchers began by pumped rubidium atoms into a vacuum chamber, then used lasers to cool the cloud of atoms to just a few degrees above absolute zero. Using extremely weak laser pulses, they then fired single photons into the cloud of atoms.

As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.

They seem to be creating a region that appears to be unaffected by their local field, but we know that that is impossible. Their experiment is transparent to the charge field, and cannot be isolated from it. I certainly do not believe that they are tracking the progress of a single individual photon, nor do I believe they are tracking photon pairs.

I suspect that, as in the other article, they are also confusing single spin electrons with photons.

While the article here is probably not a valid demonstration of paired photons, the idea has not not yet been shown to me to be wrong. I still believe that higher spin photons result from the addition of many individual photons. That continued additions result in electrons and higher matter.

I'm now having to go back re-read a lot of papers. I did find this one a good re-read:----------

The Wavelength and Frequency of Light are Reversed

When the path difference between the light from adjacent slits is equal to half the frequency, υ/2, the frequencies will all be out of phase, and thus will cancel each other to create points of minimum intensity. Similarly, when the path difference is υ, the phases will add together and maxima will occur.

Wow, that begins to make more sense already. No one has ever explained how wavelengths could physically stack, even if real photons were colliding. But with spins it is quite easy to visualize. Spins could stack or cancel in collision, because they can transfer energy in a direct mechanical way. How do wavelengths stack or cancel in collision? A wavelength is just a distance—either in my theory or in the mainstream theory—and you can't sum distances into an increased energy. But since in my theory the frequency is actually a measurement of spin velocity, the frequencies can be summed into an increased energy. Energy is not a function of distance, but it is a function of velocity. As in the equation E = ½ mv2.

You will ask me to clarify that. If the wavelength is the spin radius, then frequency is the number of times per second (say) that a point on the spin circumference returns to the same spot. And if that is true, then the frequency is just another measurement of the velocity of that point on the spin circumference. Frequency is measured as 1/s, say, with the 1 unassigned as a matter of distance. But if we know the radius, then we can assign the 1 to some real number, like 1 meter, which gives us a velocity. Given a spin and a radius of spin, a frequency gives us a velocity. So with spin, the frequency and the velocity are actually the same thing. And if the thing that is spinning has any mass, then the velocity will give us an energy. I have shown that the photon has a mass, so the velocity does give us an energy. This explains how the photon has energy.

And it explains how the photon increases its energy. I have shown that photons increase energy by stacking spins. Once the tangential velocity of our point on the circumference reaches c, it cannot increase any more. If the photon wants to add energy from a collision, it has to add another spin on top of the existing spin. It does that by going beyond that spin, so that the second spin has twice the radius of the first. But this means that a photon with more radius has more energy, and less frequency. The variables have reversed.

....

What is actually happening in the interferometer is that the light is being split into two parts. One part is forced to take a path slightly longer than the other, then the paths are recombined. Currently this is said to cause a wavelength discrepancy, which shows up as interference or fringes. But what is happening is that the spins are being thrown off, so that when the light is recombined, half of it is incoherent regarding spin. If we treat the photons as Feynman did—as little clocks—half the clocks will be pointing to 2 and half will be pointing to 3, say. They will still have the same speed and energy, but they will be out of spin phase. This solves this problem the same way it solved the partial reflection problem, because it explains the mechanics beneath Feynman's sumovers. It matters where in its spin cycle the photon is, because the photon is composed of stacked spins. By knowing where in its spin cycle the photon is, we can tell where the body of the photon is inside the spins. Consult Chris Wheeler's animation again, and you can see that the body of the photon is never at the center of the spins. This explains why being at 2 in the spin cycle is not the same as being at 3. The stacked spins give the photon a varying momentum. In other words, if the photon body is forward of center in collision, the photon will act very slightly differently than if the photon body is behind center.

To visualize the interferometer problem, imagine all the photons recombined into one beam after being reflected by the central mirror, traveling side by side once more as they approach the detector at the end. As they move along, they constantly jostle one another. Since the photons don't all hit the same spot on the mirror, they don't have precisely the same trajectory, and some variation is the result. So they do not travel in perfectly parallel trajectories. In short, they jostle. Well, when they collide side-to-side, the outer spins meet. This meeting of spins is what creates what we call interference. The spins can damp or augment, creating what we call peaks and troughs. And the distance between peaks and troughs in an interferometer will be determined by the relative difference in energy of the spins. If we have photons with a fast spin rate (or a higher spin frequency), larger gaps in the data will be produced. Larger fringe gaps will be the result.

http://www.milesmathis.com/freq.pdf

Also:-----------

SUPERPOSITION AGAIN

Some will complain that my explanation requires spin, whereas the current theory gives the photon a wave, not a spin. My answer is that it doesn't matter one way or the other. I believe the photon is spinning, and have shown theoretical and physical proof of it elsewhere, but my explanation here doesn't require you to believe it. The spin in this explanation simply allows me to show the wave more easily. The standard explanation of superposition comes from Feynman, and it is likely these youtube people are reading something by Feynman off the internet as they make their film. Well, Feynman also invented a thing called the shrink-and-turn method, which I pull apart in another paper. To illustrate the wave, Feynman uses little clocks, much like I have here. That is, he draws a circle with numbers on it and lets that stand for the wave as the photon travels. He doesn't call it a wave, true, but it works just like my wave here. His method works precisely because it mirrors my mechanics here. Well, take the little circles above as waves if you like, rather than spins. Spins create waves in a direct manner, so they are great for illutrating waves even if you don't like spins. If you don't want to assign the waves to spins, fine with me. Assign them to wobbles or leaps or hiccups or to nothing. I don't care. The point is, I solved the problem with diagrams, mechanically, without interference, without ghost particles, without multiple paths, without spooky forces, and without mystification or magic.

And finally, as a bonus, I give you the fact that the current explanation of superposition, using light interfering with itself, contradicts the current explanation of the Sagnac Effect. Wikipedia admits that the Sagnac interference math is the same both before and after Relativity. Classical physics made the same predictions as post-classical physics, regarding this effect. And, since the Sagnac Effect already had a satisfactory explanation and math before quantum physics, it didn't require the sort of explanations that have been devised for superposition. This despite the fact that the two experiments have much in common, as you see, using mirrors and beam splitters (a half-silvered mirror is a sort of splitter) and square circuits. The reason this contradicts the Sagnac Effect is that, to be consistent, we have to take the quantum explanation into that experiment as well. We can't have light interfering with itself in some cases and not interfering with itself in other similar cases, just to suit sloppy theorists. If light takes all possible paths, why doesn't it do so in the Sagnac experiment? If we let light take both paths in the Sagnac experiment, we immediately ruin our math and our explanation. Instead of getting light where we need it, we get light where we don't need it. We have too much light on both paths, and the result is either a total cancellation or a big mess. This is the problem with so many of the current jerry-rigged theories: they are very problem specific, and the magicians just hope you don't try to universalize them, and apply them to similar problems. Because if you do, you find out that they are completely ad hoc, and therefore physically false.

To read more on this, you may go to my paper on entanglement, where I analyze and solve the problem, using a hint from Feynman and my quantum spin equations.

More recently, I have blown apart the CHSH Bell tests, unveiling the terrible mathematical cheat at the heart of these experiments. This leaves entanglement in tatters.

Addendum, July 2011: I was asked by a reader why I didn't set up some experiments to prove my theory here, and my answer was that it is unnecessary. The experiments have all been done already, they just haven't been interpreted correctly. As a further example, we have what is called a quantum eraser, by which interference patterns can be "added back" into an experiment that has "lost" them. This is done by a further polarization or turning of the photons by 45o. But of course anyone who has understood my argument here will realize that the quantum eraser is more obvious proof of my mechanics. Once we give the photons real spins, we can explain all these experiments without that much effort. To see what I mean, you may want to watch this other video at youtube, where the speaker Ron Garret talks of polarizing individual photons, of up and down photons, and so on. Of course this begs a very big question he never answers or even addresses: How can photons that are point particles in the gauge math, with no extension and no mass, be differentiated? What is up about them, or down about them? How is the polarizer sorting them, especially when they are traveling one by one? In this way, we are reminded that polarization itself is a proof of my mechanics. A point particle cannot be polarized.

I will be told that it is the wave that is polarized, not the particle, but that is just dodging the begged question one more time. Neither the old quantum mechanics nor any of the updates ever bother to tell us how point particles with no radius can create waves, or move in a wave motion. My mechanics explains it, but my mechanics requires a photon with a radius, and with several stacked spins. Without them, mainstream physicists can only rush by this basic question. I have already told you why they do this in about a hundred papers: they are hiding behind the math. If they bring the mechanics back to the front, and let you see all these existing questions in a full light, their famous math begins to melt. Ron Garret calls the squared amplitude in the wave equation a hack, but all the math is hacked from top to bottom, as I have shown.

Again, the thing to take from this addendum is that polarization and superposition are both proof of real photon spin. To create quantum erasers and things like that, each individual photon must have a wavelength. I repeat, not just the wave front, or the wave packet, but each individual photon. This must mean that the polarizers are working upon individual photons, not on wave fronts or fields of photons. And for that to be possible, each photon must have a radius. A photon with no mass and no radius is undifferentiable. In other words, there is no way for a polarizer or other detector or filter to know one photon from another. You cannot tell one point from another. And this means that photons must have mass and radius. And this means that the math of QED, as we know it, comes tumbling down. Ron Garret thinks he deserves a Nobel Prize for noticing that entanglement is a measurement, but he fails to notice that QED needs more than a tweek. It needs a complete overhaul, from the baseboards up. We have to throw out all the math and all the theory and start over from the beginning.[size=32] *http://www.youtube.com/watch?v=qpQABLRCU_0 [/size]